Composite Sucker Rod Assemblies

ABSTRACT

Sucker rod assemblies are provided. A sucker rod assembly includes one or more continuous fiber reinforced thermoplastic rods. Each rod has a core comprising a plurality of generally unidirectionally oriented continuous fibers embedded in a thermoplastic resin. A sucker rod assembly further includes a first end fitting and a second end fitting, at least one of which is connected to the plurality of continuous fiber reinforced thermoplastic rods. Each rod has an ultimate tensile strength of between approximately 280,000 pounds per square inch and approximately 370,000 pounds per square inch, and the continuous fibers have a ratio of ultimate tensile strength to mass per unit length of greater than about 1,000 Megapascals per gram per meter. The continuous fibers constitute from about 25 wt. % to about 80 wt. % of each rod, and the thermoplastic resin constitutes from about 20 wt. % to about 75 wt. % of each rod.

RELATED APPLICATIONS

The present application claims priority to U.S. Provisional ApplicationSer. No. 62/102,796, filed on Jan. 13, 2015, which is incorporated byreference herein in its entirety.

BACKGROUND OF THE INVENTION

A sucker rod is a rod uses in the oil and gas industry to join togethersurface and downhole components of a reciprocating piston pump installedin an oil well. In most cases, a number of sucker rods are connectedtogether, end-to-end, to obtain the necessary length between the surfaceand downhole components. Each sucker rod can including fittings on eachend of the rod in order to facilitate the connection to other suckerrods and the surface and downhole components.

Many known sucker rods are formed from metals, such as steel. However,there are significant problems with the use of such sucker rods. Forexample, metal sucker rods are heavy and have relatively smallstrength-to-weight ratios. Additionally, the chemical and temperatureresistance capabilities of metal sucker rods are relatively low,particularly when subjected to oil well environments. Further, metalsucker rods are very susceptible to mechanical wear during operation.Still further, the requirement that a number of sucker rods of limitedlengths be connected together to obtain longer necessary lengthsintroduces weak spots into the assembly, due to the connection jointsbetween the various sucker rods.

More recently, fiberglass sucker rods have been introduced. While thesesucker rods have addressed some of the issues raised above, manyconcerns remain. Additionally, known fiberglass sucker rods arerelatively stiff, and thus cannot be spooled for transportationpurposes, etc.

Accordingly, improved sucker rods are desired in the art. In particular,sucker rods which have improved strength-to-weight ratios, chemical andtemperature resistance capabilities, mechanical wear resistance, andflexibility, and which can have relatively longer lengths which meetapplication requirements, would be advantageous.

SUMMARY OF THE INVENTION

In accordance with one embodiment of the present disclosure, a suckerrod assembly is provided. The sucker rod assembly includes a pluralityof continuous fiber reinforced thermoplastic rods arranged in a strandedbundle. Each of the plurality of continuous fiber reinforcedthermoplastic rods has a core which includes a plurality of generallyunidirectionally oriented continuous fibers embedded in a thermoplasticresin. The sucker rod assembly further includes a first end fitting anda second end fitting, at least one of the first and second end fittingsconnected to the plurality of continuous fiber reinforced thermoplasticrods. Each of the plurality of rods has an ultimate tensile strength ofbetween approximately 280,000 pounds per square inch and approximately370,000 pounds per square inch. The continuous fibers constitute fromabout 25 wt. % to about 80 wt. % of each of the plurality of rods andthe thermoplastic resin constitutes from about 20 wt. % to about 75 wt.% of each of the plurality of rods.

In accordance with another embodiment of the present disclosure, asucker rod assembly is provided. The sucker rod assembly includes asingle monolithic continuous fiber reinforced thermoplastic rod. Thecontinuous fiber reinforced thermoplastic rod has a core which includesa plurality of generally unidirectionally oriented continuous fibersembedded in a thermoplastic resin. The sucker rod assembly furtherincludes a first end fitting and a second end fitting, at least one ofthe first and second end fittings connected to the continuous fiberreinforced thermoplastic rod. The continuous fiber reinforcedthermoplastic rod has an ultimate tensile strength of betweenapproximately 280,000 pounds per square inch and approximately 370,000pounds per square inch. The continuous fibers constitute from about 25wt. % to about 80 wt. % of the rod and the thermoplastic resinconstitutes from about 20 wt. % to about 75 wt. % of the rod.

In some exemplary embodiments, the continuous fibers of a rod of asucker rod assembly of the present disclosure have a ratio of ultimatetensile strength to mass per unit length of greater than about 1,000Megapascals per gram per meter. For example, in some exemplaryembodiments, the continuous fibers of a rod of a sucker rod assembly ofthe present disclosure are carbon fibers.

In some exemplary embodiments, the thermoplastic resin of a rod of asucker rod assembly of the present disclosure includes a polyarylenesulfide, such as polyphenylene sulfide.

In some exemplary embodiments, a rod of a sucker rod assembly of thepresent disclosure includes a capping layer surrounding the core of therod. For example, in some exemplary embodiments, the capping layer mayinclude polyetherether ketone and be free from fibers.

Other features and aspects of the present invention are set forth ingreater detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof to one skilled in the art, is set forth moreparticularly in the remainder of the specification, including referenceto the accompanying figures, in which:

FIG. 1 is a side view, partially in cross-section, of a wellbore havinga sucker rod assembly connected between a pump and a pump driveaccording to one embodiment of the present disclosure;

FIG. 2 is a perspective broken view of a sucker rod assembly accordingto one embodiment of the present disclosure;

FIG. 3 is a perspective broken view of a sucker rod assembly accordingto another embodiment of the present disclosure;

FIG. 4 is a schematic illustration of an impregnation system inaccordance with one embodiment of the present disclosure;

FIG. 5 is a perspective view of a die in accordance with one embodimentof the present disclosure;

FIG. 6 is a cross-sectional view of the die shown in FIG. 5;

FIG. 7 is an exploded view of a manifold assembly and gate passage for adie in accordance with one embodiment of the present disclosure;

FIG. 8 is a perspective view of one embodiment of a second impregnationplate at least partially defining an impregnation zone in accordancewith one embodiment of the present disclosure;

FIG. 9 is a close-up cross-sectional view of a portion of animpregnation zone in accordance with one embodiment of the presentdisclosure;

FIG. 10 is a close-up cross-sectional view of a downstream end portionof an impregnation zone in accordance with one embodiment of the presentdisclosure;

FIG. 11 is a perspective view of a land zone in accordance with oneembodiment of the present disclosure;

FIG. 12 is a perspective view of a land zone in accordance with oneembodiment of the present disclosure;

FIG. 13 is a schematic illustration of one embodiment of a pultrusionsystem that may be employed in the present invention;

FIG. 14 is a top cross-sectional view of one embodiment of variouscalibration dies that may be employed in accordance with the presentinvention;

FIG. 15 is a side cross-sectional view of one embodiment of acalibration die that may be employed in accordance with the presentinvention;

FIG. 16 is a front view of a portion of one embodiment of a calibrationdie that may be employed in accordance with the present invention;

FIG. 17 is a front view of one embodiment of forming rollers that may beemployed in accordance with the present invention;

FIG. 18 is a perspective view of a tape in accordance with oneembodiment of the present disclosure;

FIG. 19 is a cross-sectional view of a tape in accordance with oneembodiment of the present disclosure; and

FIG. 20 is a perspective cross-sectional view of a composite rod formedin accordance with one embodiment of the present disclosure.

Repeat use of reference characters in the present specification anddrawings is intended to represent the same or analogous features orelements of the present invention.

DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS

It is to be understood by one of ordinary skill in the art that thepresent discussion is a description of exemplary embodiments only, andis not intended as limiting the broader aspects of the presentinvention.

Generally speaking, the present disclosure is directed to sucker rodassemblies. A sucker rod assembly in accordance with the presentdisclosure is formed from one or more continuous fiber reinforcedthermoplastic (“CFRT”) rods. In some embodiments, a plurality of CFRTrods may be utilized, with the rods arranged for example in a strandedbundle. In other embodiments, a single monolithic CFRT rod may beutilized. In exemplary embodiments, the CFRT rods may include apolyarylene sulfide, such as polyphenylene sulfide, in or as thethermoplastic resin. Further, in exemplary embodiments, the CFRT rodsmay utilize carbon fibers embedded in the thermoplastic resin.

The use of such rods in sucker rod assemblies in accordance with thepresent disclosure provides numerous advantages over previously knownsucker rods. For example, the use of CFRT materials provides lightweightand strong rods, thus increasing the strength-to-weight ratios of theresulting sucker rod assemblies. Further, as discussed herein, CFRT rodsformed in accordance with the present disclosure have excellentflexibility, thus allowing spooling of the resulting sucker rodassemblies. Additionally, CFRT rods formed in accordance with thepresent disclosure can be provided at relatively long lengths, which canbe adjusted to meet application requirements. Thus, resulting sucker rodassemblies may advantageously not require increased connections andresulting weak spots, due to the ability of the CFRT rods to havelengths which are adapted to fit the requirements of particularapplications.

Still further, CFRT rods formed in accordance with the presentdisclosure may have improved chemical and temperature resistancecapabilities. For example, each rod may include a core and a cappinglayer surrounding and bonded to the core. This capping layer may protectthe rod generally from harsh environmental conditions, and may furtherimprove the wear resistance of the rod. In exemplary embodiments, forexample, a capping layer may include polyetherether ketone, and may befree from fibers.

Referring now to FIG. 1, one embodiment of a sucker rod assembly 10 ofthe present disclosure being utilized in an oil and gas application, andspecifically in a downhole application, is illustrated. As shown, suckerrod assembly 10 extends between a pump drive 12 and a pump 14. At leasta portion of the sucker rod assembly 10 extends within and through awellbore 16. As further illustrated, a sucker rod assembly 10 inaccordance with the present disclosure may include a first end fitting20 and a second end fitting 22, which may be connected to the one ormore rods of the sucker rod assembly 10. In exemplary embodiments, onlya single sucker rod assembly 10 is required for a downhole application,with the fittings 20, 22 coupled to the pump drive 12 and pump 14 asillustrated. In alternative embodiments, however, multiple sucker rodassemblies 10 may be utilized, with the fittings 20, 22 thereofconnected to each other to form a string of sucker rod assemblies 10.

FIGS. 2 and 3 illustrate embodiments of a sucker rod assembly 10 inaccordance with the present disclosure. For example, FIG. 2 illustratesa sucker rod assembly 10 which includes a single, monolithic compositerod 750 extending between and connected to a first end fitting 20 and asecond end fitting 22. The fittings 20, 22 may be connected to therespective ends of the rod 750. As illustrated, for example, the ends ofthe rod 750 may fit within the fittings 20, 22, and the fittings 20, 22may generally surround the ends of the rod 750. The ends of the rod 750may be press-fit within or otherwise connected (via mechanicalfasteners, adhesives, etc.) to the fittings 20, 22.

FIG. 3 illustrates a sucker rod assembly 10 which includes a pluralityof composite rods 750 arranged in a stranded bundle. Each of theplurality of rods 750 is in contact with neighboring rods 750 within thebundle, as illustrated. Notably, in the arrangement illustrated, sevenrods 750 are utilized, with six rods 750 surrounding a central rod 750.In other embodiments, 19 rods 750 can be utilized, such that for examplean outer layer of 12 rods surrounds the six rods 750, or 37 or 49 rods750 having similar arrangements can be utilized. Still further, however,it should be understood that any suitable number of rods 750 may beutilized in any suitable stranded bundle arrangement. The plurality ofrods 750 may extend between and be connected to a first end fitting 20and a second end fitting 22. The fittings 20, 22 may be connected to therespective ends of the rods 750. As illustrated, for example, the endsof the rods 750 may fit within the fittings 20, 22, and the fittings 20,22 may generally surround the ends of the rods 750. The ends of the rods750 may be press-fit within or otherwise connected (via mechanicalfasteners, adhesives, etc.) to the fittings 20, 22.

Any suitable fittings 20, 22 may be utilized in a sucker rod assembly 10in accordance with the present disclosure. For example, FIGS. 2 and 3illustrate simple, tubular fittings. First end fitting 20 is illustratedas a male fitting having male threads, while second end fitting 22 isillustrated as a female fitting having female threads. Alternatively,any suitable fittings having suitable male and/or female couplingapparatus may be utilized for the fittings 20, 22. In exemplaryembodiments, the fittings 20, 22 may be formed from a suitable metal,such as steel. Alternatively, however, any suitable materials, includepolymers such as thermoplastics as discussed herein, may be utilized.

Referring now to FIG. 20, one embodiment of a rod 750 for use in asucker rod assembly 10 is presented. As can be seen, the rod 750includes a core 760 formed from a continuous fiber reinforcedthermoplastic (“CFRT”) material and a capping layer 800 that generallysurrounds and is bonded to the core 760. Capping layer 800 may extendaround the perimeter of the core 760 and define an external surface ofthe rod 750.

As illustrated, the rod 750 has a generally circular shape and includesa core 760 formed from one or more consolidated rovings 142. By“generally circular”, it is generally meant that the aspect ratio of therod (height divided by the width) is typically from about 1.0 to about1.5, and in some embodiments, about 1.0. Due to selective control overthe process used to impregnate fiber rovings and form tapes 152, 156 asdiscussed herein, as well the process for compressing and shaping thetape(s) into a preform and finally into a core 760, as discussed furtherherein, the rod 750 and core 760 thereof may possess a relatively evendistribution of resin 214 across along its entire length. This alsomeans that the continuous fibers are distributed in a generally uniformmanner about a longitudinal central axis “L” of the core 760. As shownin FIG. 20, for example, the core 760 includes continuous fibers 400embedded within a thermoplastic matrix 214. The fibers 400 aredistributed generally uniformly about the longitudinal axis “L.” Itshould be understood that only a few fibers are shown in FIG. 20, andthat the core 760 will typically contain a substantially greater numberof uniformly distributed fibers.

The cross-sectional thickness (“T”) of the rod 750 may be strategicallyselected to help achieve a particular strength. For example, the rod 750may have a thickness (e.g., diameter) of from about 0.1 to about 40millimeters, in some embodiments from about 0.5 to about 30 millimeters,and in some embodiments, from about 1 to about 10 millimeters. Thethickness of the capping layer 800 depends on the intended function ofthe part, but is typically from about 0.01 to about 10 millimeters, andin some embodiments, from about 0.02 to about 5 millimeters. Regardless,the total cross-sectional thickness or height of the rod typicallyranges from about of from about 0.1 to about 50 millimeters, in someembodiments from about 0.5 to about 40 millimeters, and in someembodiments, from about 1 to about 20 millimeters. While the rod 750 maybe substantially continuous in length, the length of the rod is oftenpractically limited by the spool onto which it will be wound and storedor the length of the continuous fibers. For example, the length oftenranges from about 1000 to about 5000 meters, although even greaterlengths are certainly possible.

Referring still to FIG. 20, the CFRT material of the core 760 includes athermoplastic material or resin and a plurality of continuous fibersembedded therein. Suitable thermoplastic materials for use in rodsinclude, for instance, polyolefins (e.g., polypropylene,propylene-ethylene copolymers, etc.), polyesters (e.g., polybutyleneterephalate (“PBT”)), polycarbonates, polyamides (e.g., PA12, Nylon™),polyether ketones (e.g., polyether ether ketone (“PEEK”)),polyetherimides, polyarylene ketones (e.g., polyphenylene diketone(“PPDK”)), liquid crystal polymers, polyarylene sulfides (e.g.,polyphenylene sulfide (“PPS”), poly(biphenylene sulfide ketone),poly(phenylene sulfide diketone), poly(biphenylene sulfide), etc.),fluoropolymers (e.g., polytetrafluoroethylene-perfluoromethylvinyletherpolymer, perfluoro-alkoxyalkane polymer, petrafluoroethylene polymer,ethylene-tetrafluoroethylene polymer, etc.), polyacetals, polyurethanes,polycarbonates, styrenic polymers (e.g., acrylonitrile butadiene styrene(“ABS”)), and so forth.

The thermoplastic material of the core 760 may further include aplurality of fibers embedded therein to reinforce the thermoplasticmaterial. In exemplary embodiments, the CFRT material includescontinuous fibers, although it should be understood that long fibers mayadditionally be included therein. The fibers may be dispersed in thethermoplastic material to form the CFRT material. As used therein, theterm “long fibers” generally refers to fibers, filaments, yarns, orrovings that are not continuous, and as opposed to “continuous fibers”which generally refer to fibers, filaments, yarns, or rovings having alength that is generally limited only by the length of a part. Thefibers dispersed in the polymer material may be formed from anyconventional material known in the art, such as metal fibers, glassfibers (e.g., E-glass, A-glass, C-glass, D-glass, AR-glass, R-glass,S-glass such as S1-glass or S2-glass), carbon fibers (e.g., graphite),boron fibers, ceramic fibers (e.g., alumina or silica), aramid fibers(e.g., Kevlar® marketed by E. I. duPont de Nemours, Wilmington, Del.),synthetic organic fibers (e.g., polyamide, polyethylene, paraphenylene,terephthalamide, polyethylene terephthalate and polyphenylene sulfide),and various other natural or synthetic inorganic or organic fibrousmaterials known for reinforcing polymer compositions. Glass fibers,carbon fibers, and aramid fibers are particularly desirable. Inexemplary embodiments, the continuous fibers may be generallyunidirectional.

A rod 750 in accordance with the present disclosure may be formed usingany suitable process or apparatus. Exemplary embodiments of suitableprocesses and apparatus, such as pultrusion processes and apparatus, forforming a tape and rod according to the present disclosure are discussedin detail below.

Referring to FIG. 4, one embodiment of such an extrusion device isshown. More particularly, the apparatus includes an extruder 130containing a screw shaft 134 mounted inside a barrel 132. A heater 136(e.g., electrical resistance heater) is mounted outside the barrel 132.During use, a feedstock 137 is supplied to the extruder 130 through ahopper 138. The feedstock is formed from a thermoplastic material asdiscussed above. The feedstock 137 is conveyed inside the barrel 132 bythe screw shaft 134 and heated by frictional forces inside the barrel132 and by the heater 136. Upon being heated, the feedstock 137 exitsthe barrel 132 through a barrel flange 138 and enters a die flange 139of an impregnation die 150.

A continuous fiber roving 142 or a plurality of continuous fiber rovings142 are supplied from a reel or reels 144 to die 150. The rovings 142are generally positioned side-by-side, with minimal to no distancebetween neighboring rovings, before impregnation. The feedstock 137 mayfurther be heated inside the die by heaters 146 mounted in or around thedie 150. The die is generally operated at temperatures that aresufficient to cause and/or maintain the proper melt temperature for thethermoplastic material, thus allowing for the desired level ofimpregnation of the rovings by the thermoplastic material. Typically,the operation temperature of the die is higher than the melt temperatureof the thermoplastic material, such as at temperatures from about 200°C. to about 450° C. When processed in this manner, the continuous fiberrovings 142 become embedded in the thermoplastic material, which may bea resin 214 processed from the feedstock 137. The mixture may then exitthe impregnation die 150 as wetted composite, extrudate, or tape 152.

As used herein, the term “roving” generally refers to a bundle ofindividual fibers 400. The fibers 400 contained within the roving can betwisted or can be straight. The rovings may contain a single fiber typeor different types of fibers 400. Different fibers may also be containedin individual rovings or, alternatively, each roving may contain adifferent fiber type. The continuous fibers employed in the rovingspossess a high degree of tensile strength relative to their mass. Forexample, the ultimate tensile strength of the fibers is typically fromabout 1,000 to about 15,000 Megapascals (“MPa”), in some embodimentsfrom about 2,000 MPa to about 10,000 MPa, and in some embodiments, fromabout 3,000 MPa to about 6,000 MPa. Such tensile strengths may beachieved even though the fibers are of a relatively light weight, suchas a mass per unit length of from about 0.05 to about 2 grams per meter,in some embodiments from about 0.4 to about 1.5 grams per meter. Theratio of ultimate tensile strength to mass per unit length may thus begreater than about 1,000 Megapascals per gram per meter (“MPa/g/m”), insome embodiments greater than about 4,000 MPa/g/m, and in someembodiments from about 5,000 to about 20,000 MPa/g/m. Carbon fibers areparticularly suitable for use as the continuous fibers, which typicallyhave a tensile strength to mass ratio in the range of from about 5,000to about 7,000 MPa/g/m. The continuous fibers often have a nominaldiameter of about 4 to about 35 micrometers, and in some embodiments,from about 9 to about 35 micrometers. The number of fibers contained ineach roving can be constant or vary from roving to roving. Typically, aroving contains from about 1,000 fibers to about 50,000 individualfibers, and in some embodiments, from about 5,000 to about 30,000fibers.

A pressure sensor 147 may sense the pressure near the impregnation die150 to allow control to be exerted over the rate of extrusion bycontrolling the rotational speed of the screw shaft 134, or the feedrate of the feeder. That is, the pressure sensor 147 is positioned nearthe impregnation die 150, such as upstream of the manifold assembly 220,so that the extruder 130 can be operated to deliver a correct amount ofresin 214 for interaction with the fiber rovings 142. After leaving theimpregnation die 150, impregnated rovings 142 or the extrudate or tape152, which may comprises the CFRT material, may enter an optionalpre-shaping or guiding section (not shown) and/or a preheating device tocontrol the temperature of the extrudate before entering a nip formedbetween two adjacent rollers 190. Although optional, the rollers 190 canhelp to consolidate the impregnated rovings 142 into a tape 156 orconsolidate the tape 152 into a final tape 156, as well as enhance fiberimpregnation and squeeze out any excess voids. In addition to therollers 190, other shaping devices may also be employed, such as a diesystem. Regardless, the resulting consolidated tape 156 is pulled bytracks 162 and 164 mounted on rollers. The tracks 162 and 164 also pullthe impregnated rovings 142 or tape 152 from the impregnation die 150and through the rollers 190. If desired, the consolidated tape 156 maybe wound up at a section 171. Generally speaking, the resulting tapesare relatively thin and typically have a thickness of from about 0.05 toabout 1 millimeter, in some embodiments from about 0.1 to about 0.8millimeters, and in some embodiments, from about 0.1 to about 0.4millimeters.

Perspective views of one embodiment of a die 150 according to thepresent disclosure are further shown in FIGS. 4 and 5. As shown, resin214 is flowed into the die 150 as indicated by resin flow direction 244.The resin 214 is distributed within the die 150 and then interacted withthe rovings 142. The rovings 142 are traversed through the die 150 inroving run direction 282, and are coated with resin 214. The rovings 142are then impregnated with the resin 214, and these impregnated rovings142 exit the die 150. In some embodiments, as shown in FIG. 4, theimpregnated rovings 142 are connected by the resin 214 and thus exit astape 152. In other embodiments, as shown in FIGS. 5 and 6, theimpregnated rovings 142 exit the die separately, each impregnated withinresin 214.

Within the impregnation die, it is generally desired that the rovings142 are traversed through an impregnation zone 250 to impregnate therovings with the polymer resin 214. In the impregnation zone 250, thepolymer resin may be forced generally transversely through the rovingsby shear and pressure created in the impregnation zone 250, whichsignificantly enhances the degree of impregnation. This is particularlyuseful when forming a composite from tapes of high fiber content, suchas about 35% weight fraction (“Wf”) or more, and in some embodiments,from about 40% Wf or more. Typically, the die 150 will include aplurality of contact surfaces 252, such as for example at least 2, atleast 3, from 4 to 7, from 2 to 20, from 2 to 30, from 2 to 40, from 2to 50, or more contact surfaces 252, to create a sufficient degree ofpenetration and pressure on the rovings 142. Although their particularform may vary, the contact surfaces 252 typically possess a curvilinearsurface, such as a curved lobe, pin, etc. The contact surfaces 252 arealso typically made of a metal material.

FIG. 6 shows a cross-sectional view of an impregnation die 150. Asshown, the impregnation die 150 includes a manifold assembly 220 and animpregnation section. The impregnation section includes an impregnationzone 250. In some embodiments, the impregnation section additionallyincludes a gate passage 270. The manifold assembly 220 is provided forflowing the polymer resin 214 therethrough. For example, the manifoldassembly 220 may include a channel 222 or a plurality of channels 222.The resin 214 provided to the impregnation die 150 may flow through thechannels 222.

As shown in FIG. 7, in exemplary embodiments, at least a portion of eachof the channels 222 may be curvilinear. The curvilinear portions mayallow for relatively smooth redirection of the resin 214 in variousdirections to distribute the resin 214 through the manifold assembly220, and may allow for relatively smooth flow of the resin 214 throughthe channels 222. Alternatively, the channels 222 may be linear, andredirection of the resin 214 may be through relatively sharp transitionareas between linear portions of the channels 222. It should further beunderstood that the channels 222 may have any suitable shape, size,and/or contour.

The plurality of channels 222 may, in exemplary embodiments as shown inFIG. 7, be a plurality of branched runners 222. The runners 222 mayinclude a first branched runner group 232. The first branched runnergroup 232 includes a plurality of runners 222 branching off from aninitial channel or channels 222 that provide the resin 214 to themanifold assembly 220. The first branched runner group 232 may include2, 3, 4 or more runners 222 branching off from the initial channels 222.

If desired, the runners 222 may include a second branched runner group234 diverging from the first branched runner group 232, as shown. Forexample, a plurality of runners 222 from the second branched runnergroup 234 may branch off from one or more of the runners 222 in thefirst branched runner group 232. The second branched runner group 234may include 2, 3, 4 or more runners 222 branching off from runners 222in the first branched runner group 232.

If desired, the runners 222 may include a third branched runner group236 diverging from the second branched runner group 234, as shown. Forexample, a plurality of runners 222 from the third branched runner group236 may branch off from one or more of the runners 222 in the secondbranched runner group 234. The third branched runner group 236 mayinclude 2, 3, 4 or more runners 222 branching off from runners 222 inthe second branched runner group 234.

In some exemplary embodiments, as shown, the plurality of branchedrunners 222 has a symmetrical orientation along a central axis 224. Thebranched runners 222 and the symmetrical orientation thereof generallyevenly distribute the resin 214, such that the flow of resin 214 exitingthe manifold assembly 220 and coating the rovings 142 is substantiallyuniformly distributed on the rovings 142. This desirably allows forgenerally uniform impregnation of the rovings 142.

Further, the manifold assembly 220 may in some embodiments define anoutlet region 242. The outlet region 242 is that portion of the manifoldassembly 220 wherein resin 214 exits the manifold assembly 220. Thus,the outlet region 242 generally encompasses at least a downstreamportion of the channels or runners 222 from which the resin 214 exits.In some embodiments, as shown, at least a portion of the channels orrunners 222 disposed in the outlet region 242 have an increasing area ina flow direction 244 of the resin 214. The increasing area allows fordiffusion and further distribution of the resin 214 as the resin 214flows through the manifold assembly 220, which further allows forsubstantially uniform distribution of the resin 214 on the rovings 142.Additionally or alternatively, various channels or runners 222 disposedin the outlet region 242 may have constant areas in the flow direction244 of the resin 214, or may have decreasing areas in the flow direction244 of the resin 214.

In some embodiments, as shown, each of the channels or runners 222disposed in the outlet region 242 is positioned such that resin 214flowing therefrom is combined with resin 214 from other channels orrunners 222 disposed in the outlet region 242. This combination of theresin 214 from the various channels or runners 222 disposed in theoutlet region 242 produces a generally singular and uniformlydistributed flow of resin 214 from the manifold assembly 220 tosubstantially uniformly coat the rovings 142. Alternatively, some of thechannels or runners 222 disposed in the outlet region 242 may bepositioned such that resin 214 flowing therefrom is discrete from theresin 214 from other channels or runners 222 disposed in the outletregion 242. In these embodiments, a plurality of discrete but generallyevenly distributed resin flows 214 may be produced by the manifoldassembly 220 for substantially uniformly coating the rovings 142.

As shown in FIG. 6, at least a portion of the channels or runners 222disposed in the outlet region 242 have curvilinear cross-sectionalprofiles. These curvilinear profiles allow for the resin 214 to begradually directed from the channels or runners 222 generally downwardtowards the rovings 142. Alternatively, however, these channels orrunners 222 may have any suitable cross-sectional profiles.

As further illustrated in FIGS. 6 and 7, after flowing through themanifold assembly 220, the resin 214 may flow through gate passage 270.Gate passage 270 is positioned between the manifold assembly 220 and theimpregnation zone 250, and is provided for flowing the resin 214 fromthe manifold assembly 220 such that the resin 214 coats the rovings 142.Thus, resin 214 exiting the manifold assembly 220, such as throughoutlet region 242, may enter gate passage 270 and flow therethrough.

In some embodiments, as shown in FIG. 6, the gate passage 270 extendsvertically between the manifold assembly 220 and the impregnation zone250. Alternatively, however, the gate passage 270 may extend at anysuitable angle between vertical and horizontal such that resin 214 isallowed to flow therethrough.

Further, as shown in FIG. 6, in some embodiments at least a portion ofthe gate passage 270 has a decreasing cross-sectional profile in theflow direction 244 of the resin 214. This taper of at least a portion ofthe gate passage 270 may increase the flow rate of the resin 214 flowingtherethrough before it contacts the rovings 142, which may allow theresin 214 to impinge on the rovings 142. Initial impingement of therovings 142 by the resin 214 provides for further impregnation of therovings, as discussed below. Further, tapering of at least a portion ofthe gate passage 270 may increase backpressure in the gate passage 270and the manifold assembly 220, which may further provide more even,uniform distribution of the resin 214 to coat the rovings 142.Alternatively, the gate passage 270 may have an increasing or generallyconstant cross-sectional profile, as desired or required.

Upon exiting the manifold assembly 220 and the gate passage 270 of thedie 150 as shown in FIG. 6, the resin 214 contacts the rovings 142 beingtraversed through the die 150. As discussed above, the resin 214 maysubstantially uniformly coat the rovings 142, due to distribution of theresin 214 in the manifold assembly 220 and the gate passage 270.Further, in some embodiments, the resin 214 may impinge on an uppersurface of each of the rovings 142, or on a lower surface of each of therovings 142, or on both an upper and lower surface of each of therovings 142. Initial impingement on the rovings 142 provides for furtherimpregnation of the rovings 142 with the resin 214. Impingement on therovings 142 may be facilitated by the velocity of the resin 214 when itimpacts the rovings 142, the proximity of the rovings 142 to the resin214 when the resin exits the manifold assembly 220 or gate passage 270,or other various variables.

As shown in FIG. 6, the coated rovings 142 are traversed in rundirection 282 through impregnation zone 250. The impregnation zone 250is in fluid communication with the manifold assembly 220, such asthrough the gate passage 270 disposed therebetween. The impregnationzone 250 is configured to impregnate the rovings 142 with the resin 214.

For example, as discussed above, in exemplary embodiments as shown inFIGS. 6 and 8 through 10, the impregnation zone 250 includes a pluralityof contact surfaces 252. The rovings 142 are traversed over the contactsurfaces 252 in the impregnation zone. Impingement of the rovings 142 onthe contact surface 252 creates shear and pressure sufficient toimpregnate the rovings 142 with the resin 214 coating the rovings 142.

In some embodiments, as shown in FIGS. 6, 9 and 10, the impregnationzone 250 is defined between two spaced apart opposing impregnationplates 256 and 258, which may be included in the impregnation section.First plate 256 defines a first inner surface 257, while second plate258 defines a second inner surface 259. The impregnation zone 250 isdefined between the first plate 256 and the second plate 258. Thecontact surfaces 252 may be defined on or extend from both the first andsecond inner surfaces 257 and 259, or only one of the first and secondinner surfaces 257 and 259.

In exemplary embodiments, as shown in FIGS. 6, 9 and 10, the contactsurfaces 252 may be defined alternately on the first and second surfaces257 and 259 such that the rovings alternately impinge on contactsurfaces 252 on the first and second surfaces 257 and 259. Thus, therovings 142 may pass contact surfaces 252 in a waveform, tortuous orsinusoidal-type pathway, which enhances shear.

Angle 254 at which the rovings 142 traverse the contact surfaces 252 maybe generally high enough to enhance shear and pressure, but not so highto cause excessive forces that will break the fibers. Thus, for example,the angle 254 may be in the range between approximately 1° andapproximately 30°, and in some embodiments, between approximately 5° andapproximately 25°.

As stated above, contact surfaces 252 typically possess a curvilinearsurface, such as a curved lobe, pin, etc. In exemplary embodiments asshown, a plurality of peaks, which may form contact surfaces 252, andvalleys are thus defined. Further, in many exemplary embodiments, theimpregnation zone 250 has a waveform cross-sectional profile. In oneexemplary embodiment as shown in FIGS. 6 and 8 through 10, the contactsurfaces 252 are lobes that form portions of the waveform surfaces ofboth the first and second plates 256 and 258 and define the waveformcross-sectional profile. FIG. 8 illustrates the second plate 258 and thevarious contact surfaces thereon that form at least a portion of theimpregnation zone 250 according to some of these embodiments.

In other embodiments, the contact surfaces 252 are lobes that formportions of a waveform surface of only one of the first or second plate256 or 258. In these embodiments, impingement occurs only on the contactsurfaces 252 on the surface of the one plate. The other plate maygenerally be flat or otherwise shaped such that no interaction with thecoated rovings occurs.

In other alternative embodiments, the impregnation zone 250 may includea plurality of pins (or rods), each pin having a contact surface 252.The pins may be static, freely rotational (not shown), or rotationallydriven. Further, the pins may be mounted directly to the surface of theplates defining the impingement zone, or may be spaced from the surface.It should be noted that the pins may be heated by heaters 143, or may beheated individually or otherwise as desired or required. Further, thepins may be contained within the die 150, or may extend outwardly fromthe die 150 and not be fully encased therein.

In further alternative embodiments, the contact surfaces 252 andimpregnation zone 250 may comprise any suitable shapes and/or structuresfor impregnating the rovings 142 with the resin 214 as desired orrequired.

As discussed, a roving 142 traversed through an impregnation zone 250according to the present disclosure may become impregnated by resin 214,thus resulting in an impregnated roving 142, and optionally a tape 152comprising at least one roving 142, exiting the impregnation zone 250,such as downstream of the contact surfaces 252 in the run direction 282.The impregnated rovings 142 and optional tape 152 exiting theimpregnation zone 250 are thus formed from a fiber impregnated polymermaterial, as discussed above.

As further shown in FIGS. 5 and 6, in some embodiments, a faceplate 290may adjoin or be adjacent to the impregnation zone 250. The faceplate290 may be positioned downstream of the impregnation zone 250 and, ifincluded, the land zone 280, in the run direction 282. The faceplate 290may contact other components of the die 150, such as the impregnationzone 250 or land zone 280, or may be spaced therefrom. Faceplate 290 isgenerally configured to meter excess resin 214 from the rovings 142.Thus, apertures in the faceplate 290, through which the rovings 142traverse, may be sized such that when the rovings 142 are traversedtherethrough, the size of the apertures causes excess resin 214 to beremoved from the rovings 142.

As shown in FIG. 4, in alternative embodiments, the die 150 may lack afaceplate 290. Further, in some embodiments, the formation andmaintenance of a tape 152 within and exited from a die 150 of thepresent disclosure may be facilitated through the lack of or removal ofa faceplate from the die 150. Removal of the faceplate 290 allows for aplurality of rovings 142 exiting a die 150 to exit as a single sheet ortape 152, rather than as separated rovings 142 due to metering throughthe faceplate. This could potentially eliminate the need to later formthese rovings 142 into such a sheet or tape 156. Removal of thefaceplate 290 may have additional advantages. For example, removal mayprevent clogging of the faceplate with resin 214, which can disrupt thetraversal of rovings 142 therethrough. Additionally, removal may allowfor easier access to the impregnation zone 250, and may thus make iteasier to introduce and reintroduce rovings 142 to the impregnation zone250 during start-up, after temporary disruptions such as due to breakageof a roving 142, or during any other suitable time period.

It should be understood that a tape 152, 156 according to the presentdisclosure may have any suitable cross-sectional shape and/or size. Forexample, such tape 152, 156 may have a generally rectangular shape, or agenerally oval or circular or other suitable polygonal or otherwiseshape. Further, it should be understood that one or more impregnatedrovings 142 having been traversed through the impregnation zone 250 maytogether form the tape 152, 156, with the resin 214 of the variousrovings 142 connected to form such tape 152, 156. The various aboveamounts, ranges, and/or ratios may thus in exemplary embodiments bedetermined for a tape 152 having any suitable number of impregnatedrovings 142 embedded and generally dispersed within resin 214.

To further facilitate impregnation of the rovings 142, they may also bekept under tension while present within the die 150, and specificallywithin the impregnation zone 250. The tension may, for example, rangefrom about 5 to about 300 Newtons, in some embodiments from about 50 toabout 250 Newtons, and in some embodiments, from about 100 to about 200Newtons per roving 142 or tow of fibers.

As shown in FIGS. 11 and 12, in some embodiments, a land zone 280 may bepositioned downstream of the impregnation zone 250 in run direction 282of the rovings 142. The rovings 142 may traverse through the land zone280 before exiting the die 150. In some embodiments, as shown in FIG.11, at least a portion of the land zone 280 may have an increasingcross-sectional profile in run direction 282, such that the area of theland zone 280 increases. The increasing portion may be the downstreamportion of the land zone 280 to facilitate the rovings 142 exiting thedie 150. Alternatively, the cross-sectional profile or any portionthereof may decrease, or may remain constant as shown in FIG. 12.

Additionally, other components may be optionally employed to assist inthe impregnation of the fibers. For example, a “gas jet” assembly may beemployed in certain embodiments to help uniformly spread a roving ofindividual fibers, which may each contain up to as many as 24,000fibers, across the entire width of the merged tow. This helps achieveuniform distribution of strength properties. Such an assembly mayinclude a supply of compressed air or another gas that impinges in agenerally perpendicular fashion on the moving rovings that pass acrossexit ports. The spread rovings may then be introduced into a die forimpregnation, such as described above.

It should be understood that tapes 152, 156 and impregnated rovings 142thereof according to the present disclosure need not be formed in thedies 150 and other apparatus as discussed above. Such dies 150 andapparatus are merely disclosed as examples of suitable equipment forforming tapes 152, 156. The use of any suitable equipment or process toform tapes 152, 156 is within the scope and spirit of the presentdisclosure.

A relatively high percentage of fibers may be employed in a tape (andresulting rod), and CFRT material thereof, to provide enhanced strengthproperties. For instance, fibers typically constitute from about 25 wt.% to about 80 wt. %, in some embodiments from about 30 wt. % to about 75wt. %, and in some embodiments, from about 35 wt. % to about 70 wt. % ofthe tape or material thereof. Likewise, polymer(s) typically constitutefrom about 20 wt. % to about 75 wt. %, in some embodiments from about 25wt. % to about 70 wt. %, and in some embodiments, from about 30 wt. % toabout 65 wt. % of the tape 152, 156. Such percentage of fibers mayadditionally or alternatively be measured as a volume fraction. Forexample, in some embodiments, the CFRT material may have a fiber volumefraction between approximately 25% and approximately 80%, in someembodiments between approximately 30% and approximately 70%, in someembodiments between approximately 40% and approximately 60%, and in someembodiments between approximately 45% and approximately 55%.

After formation of a tape 152, 156, the tape 152, 156 may be formed intoa core 760 of a rod 750. Any suitable processes and apparatus may beutilized to form a tape 152, 156 into the core 760 of a rod 750. Thespecific manner in which rovings and tapes 152, 156, are shaped may becarefully controlled to ensure that rods 750 can be formed with anadequate degree of compression and strength properties. Referring toFIG. 13, for example, one particular embodiment of a system and methodfor forming a rod are shown. In this embodiment, two tapes 152, 156 areinitially provided in a wound package on a creel 620. The creel 620 maybe an unreeling creel that includes a frame provided with horizontalspindles 622, each supporting a package. A pay-out creel may also beemployed, particularly if desired to induce a twist into the fibers. Itshould also be understood that the tape may also be formed in-line withthe formation of the rod. In one embodiment, for example, the tape 152,156 downstream of the guide assembly 510 may be directly supplied to thesystem used to form a rod. A tension-regulating device 640 may also beemployed to help control the degree of tension in the tapes 152, 156.The device 640 may include inlet plate 630 that lies in a vertical planeparallel to the rotating spindles 622 of the creel 620 and/orperpendicular to the incoming ribbons. The tension-regulating device 640may contain cylindrical bars 641 arranged in a staggered configurationso that the tape 152, 156 passes over and under these bars to define awave pattern. The height of the bars can be adjusted to modify theamplitude of the wave pattern and control tension.

The tapes 152, 156 may be heated in an oven 645 before entering aconsolidation die. Heating may be conducted using any known type ofoven, as in an infrared oven, convection oven, etc. During heating, thefibers in the tapes are unidirectionally oriented to optimize theexposure to the heat and maintain even heat across the entire tape. Thetemperature to which the tapes 152, 156 are heated is generally highenough to soften the thermoplastic polymer to an extent that the tapescan bond together. However, the temperature is not so high as to destroythe integrity of the material. The temperature may, for example, rangefrom about 100° C. to about 500° C., in some embodiments from about 200°C. to about 400° C., and in some embodiments, from about 250° C. toabout 350° C. In one particular embodiment, for example, polyphenylenesulfide (“PPS”) is used as the polymer, and the tapes are heated to orabove the melting point of PPS, which is about 285° C.

Upon being heated, the tapes 152, 156 are provided to a consolidationdie 650 that compresses them together into a preform 614, as well asaligns and forms the initial shape of the rod. As shown generally inFIG. 13, for example, the tapes 152, 156 are guided through a flowpassage 651 of the die 650 in a direction “A” from an inlet 653 to anoutlet 655. The passage 651 may have any of a variety of shapes and/orsizes to achieve the rod configuration. For example, the channel and rodconfiguration may be circular, elliptical, parabolic, etc. Within thedie 650, the tapes are generally maintained at a temperature at or abovethe melting point of the thermoplastic matrix used in the ribbon toensure adequate consolidation.

The desired heating, compression, and shaping of the tapes 152, 156 maybe accomplished through the use of a die 650 having one or multiplesections. For instance, although not shown in detail in FIG. 13, theconsolidation die 650 may possess multiple sections that functiontogether to compress and shape the tapes 152, 156 into the desiredconfiguration. For instance, a first section of the passage 651 may be atapered zone that initially shapes the material as it flows from intothe die 650. The tapered zone generally possesses a cross-sectional areathat is larger at its inlet than at its outlet. For example, thecross-sectional area of the passage 651 at the inlet of the tapered zonemay be about 2% or more, in some embodiments about 5% or more, and insome embodiments, from about 10% to about 20% greater than thecross-sectional area at the outlet of the tapered zone. Regardless, thecross-sectional of the flow passage typically changes gradually andsmoothly within the tapered zone so that a balanced flow of thecomposite material through the die can be maintained. A shaping zone mayalso follow the tapered zone that compresses the material and provides agenerally homogeneous flow therethrough. The shaping zone may alsopre-shape the material into an intermediate shape that is similar tothat of the rod, but typically of a larger cross-sectional area to allowfor expansion of the thermoplastic polymer while heated so as tominimize the risk of backup within the die 650. The shaping zone couldalso include one or more surface features that impart a directionalchange to the preform. The directional change forces the material to beredistributed resulting in a more even distribution of the fiber/resinin the final shape. This also reduces the risk of dead spots in the diethat can cause burning of the resin. For example, the cross-sectionalarea of the passage 651 at the shaping zone may be about 2% or more, insome embodiments about 5% or more, and in some embodiments, from about10% to about 20% greater than the width of the preform 614. A die landmay also follow the shaping zone to serve as an outlet for the passage651. The shaping zone, tapered zone, and/or die land may be heated to atemperature at or above that of the glass transition temperature ormelting point of the thermoplastic matrix.

If desired, a second die 660 (e.g., calibration die) may also beemployed that compresses the preform 614 into the final shape of therod. When employed, it is sometimes desired that the preform 614 isallowed to cool briefly after exiting the consolidation die 650 andbefore entering the optional second die 660. This allows theconsolidated preform 614 to retain its initial shape before progressingfurther through the system. Typically, cooling reduces the temperatureof the exterior of the rod below the melting point temperature of thethermoplastic matrix to minimize and substantially prevent theoccurrence of melt fracture on the exterior surface of the rod. Theinternal section of the rod, however, may remain molten to ensurecompression when the rod enters the calibration die body. Such coolingmay be accomplished by simply exposing the preform 614 to the ambientatmosphere (e.g., room temperature) or through the use of active coolingtechniques (e.g., water bath or air cooling) as is known in the art. Inone embodiment, for example, air is blown onto the preform 614 (e.g.,with an air ring). The cooling between these stages, however, generallyoccurs over a small period of time to ensure that the preform 614 isstill soft enough to be further shaped. For example, after exiting theconsolidation die 650, the preform 614 may be exposed to the ambientenvironment for only from about 1 to about 20 seconds, and in someembodiments, from about 2 to about 10 seconds, before entering thesecond die 660. Within the die 660, the preform is generally kept at atemperature below the melting point of the thermoplastic matrix used inthe ribbon so that the shape of the rod can be maintained. Althoughreferred to above as single dies, it should be understood that the dies650 and 660 may in fact be formed from multiple individual dies (e.g.,face plate dies).

Thus, in some embodiments, multiple individual dies 660 may be utilizedto gradually shape the material into the desired configuration. The dies660 are placed in series, and provide for gradual decreases in thedimensions of the material. Such gradual decreases allow for shrinkageduring and between the various steps.

For example, as shown in FIGS. 14 through 16, a first die 660 mayinclude one or more inlets 662 and corresponding outlets 664, as shown.Any number of inlets 662 and corresponding outlets 664 may be includedin a die 660, such as four as shown, one, two, three, five, six, ormore. An inlet 662 in some embodiments may be generally oval or circleshaped. In other embodiments, the inlet 662 may have a curvedrectangular shape, i.e., a rectangular shape with curved corners or arectangular shape with straight longer sidewalls and curved shortersidewalls. Further, an outlet 664 may be generally oval or circleshaped, or may have a curved rectangular shape. In some embodimentswherein an oval shaped inlet is utilized, the inlet 662 may have a majoraxis length 666 to minor axis length 668 ratio in a range betweenapproximately 3 to 1 and approximately 5 to 1. In some embodimentswherein an oval or circular shaped inlet is utilized, the outlet 664 mayhave a major axis length 666 to minor axis length 668 ratio in a rangebetween approximately 1 to 1 and approximately 3 to 1. In embodimentswherein a curved rectangular shape is utilized, the inlet and outlet mayhave major axis length 666 to minor axis length 668 ratios (aspectratios) between approximately 2 to 1 and approximately 7 to 1, with theoutlet 664 ratio being less than the inlet 662 ratio.

In further embodiments, the cross-sectional area of an inlet 662 and thecross-sectional area of a corresponding outlet 664 of the first die 660may have a ratio in a range between approximately 1.5 to 1 and 6 to 1.

The first die 660 thus provides a generally smooth transformation ofpolymer impregnated fiber material to a shape that is relatively similarto a final shape of the resulting rod, which in exemplary embodimentshas a circular or oval shaped cross-section. Subsequent dies, such as asecond die 660 and third die 660 as shown in FIG. 14, may provide forfurther gradual decreases and/or changes in the dimensions of thematerial, such that the shape of the material is converted to a finalcross-sectional shape of the rod. These subsequent dies 660 may bothshape and cool the material. For example, in some embodiments, eachsubsequent die 660 may be maintained at a lower temperature than theprevious dies. In exemplary embodiments, all dies 660 are maintained attemperatures that are higher than a softening point temperature for thematerial.

In further exemplary embodiments, dies 660 having relatively long landlengths 669 may be desired, due to for example desires for propercooling and solidification, which are critical in achieving a desiredrod shape and size. Relatively long land lengths 669 reduce stresses andprovide smooth transformations to desired shapes and sizes, and withminimal void fraction and bow characteristics. In some embodiments, forexample, a ratio of land length 669 at an outlet 664 to major axislength 666 at the outlet 664 for a die 660 may be in the range betweenapproximately 0 and approximately 20, such as between approximately 2and approximately 6.

The use of calibration dies 660 according to the present disclosureprovides for gradual changes in material cross-section, as discussed.These gradual changes may in exemplary embodiments ensure that theresulting product, such as a rod or other suitable product has agenerally uniform fiber distribution with relatively minimal voidfraction.

It should be understood that any suitable number of dies 660 may beutilized to gradually form the material into a profile having anysuitable cross-sectional shape, as desired or required by variousapplications.

In addition to the use of one or more dies, other mechanisms may also beemployed to help compress the preform 614 into the shape of a core 760for a rod 750. For example, forming rollers 690, as shown in FIG. 17,may be employed between the consolidation die 650 and the calibrationdie 660, between the various calibration dies 660, and/or after thecalibration dies 660 to further compress the preform 614 before it isconverted into its final shape. The rollers may have any configuration,such as pinch rollers, overlapping rollers, etc., and may be vertical asshown or horizontal rollers. Depending on the roller 690 configuration,the surfaces of the rollers 690 may be machined to impart the dimensionsof the final product, such as the rod, profile, or other suitableproduct, to the preform 614. In exemplary embodiment, the pressure ofthe rollers 690 should be adjustable to optimize the quality of thefinal product.

The rollers 690 in exemplary embodiments, such as at least the portionscontacting the material, may have generally smooth surfaces. Forexample, relatively hard, polished surfaces are desired in manyembodiments. For example, the surface of the rollers may be formed froma relatively smooth chrome or other suitable material. This allows therollers 690 to manipulate the preform 614 without damaging orundesirably altering the preform 614. For example, such surfaces mayprevent the material from sticking to the rollers, and the rollers mayimpart smooth surfaces onto the materials.

In some embodiments, the temperature of the rollers 690 is controlled.This may be accomplished by heating of the rollers 690 themselves, or byplacing the rollers 690 in a temperature controlled environment.

Further, in some embodiments, surface features 692 may be provided onthe rollers 690. The surface features 692 may guide and/or control thepreform 614 in one or more directions as it is passed through therollers. For example, surface features 692 may be provided to preventthe preform 614 from folding over on itself as it is passed through therollers 690. Thus, the surface features 692 may guide and controldeformation of the preform 614 in the cross-machine direction relativeto the machine direction A as well as in the vertical direction relativeto the machine direction A. The preform 614 may thus be pushed togetherin the cross-machine direction, rather than folded over on itself, as itis passed through the rollers 690 in the machine direction A.

In some embodiments, tension regulation devices may be provided incommunication with the rollers. These devices may be utilized with therollers to apply tension to the preform 614 in the machine direction,cross-machine direction, and/or vertical direction to further guideand/or control the preform.

As indicated above, the resulting rod is also applied with a cappinglayer to protect it from environmental conditions or to improve wearresistance. Referring again to FIG. 13, for example, such a cappinglayer may be applied via an extruder oriented at any desired angle tointroduce a thermoplastic resin into a capping die 672. To help preventa galvanic response, it is typically desired that the capping materialhas a dielectric strength of at least about 1 kilivolt per millimeter(kV/mm), in some embodiments at least about 2 kV/mm, in some embodimentsfrom about 3 kV/mm to about 50 kV/mm, and in some embodiments, fromabout 4 kV/mm to about 30 kV/mm, such as determined in accordance withASTM D149-09. Suitable thermoplastic polymers for this purpose mayinclude, for instance, polyolefins (e.g., polypropylene,propylene-ethylene copolymers, etc.), polyesters (e.g., polybutyleneterephalate (“PBT”)), polycarbonates, polyamides (e.g., Nylon™),polyether ketones (e.g., polyetherether ketone (“PEEK”)),polyetherimides, polyarylene ketones (e.g., polyphenylene diketone(“PPDK”)), liquid crystal polymers, polyarylene sulfides (e.g.,polyphenylene sulfide (“PPS”), poly(biphenylene sulfide ketone),poly(phenylene sulfide diketone), poly(biphenylene sulfide), etc.),fluoropolymers (e.g., polytetrafluoroethylene-perfluoromethylvinyletherpolymer, perfluoro-alkoxyalkane polymer, petrafluoroethylene polymer,ethylene-tetrafluoroethylene polymer, etc.), polyacetals, polyurethanes,polycarbonates, styrenic polymers (e.g., acrylonitrile butadiene styrene(“ABS”)), acrylic polymers, polyvinyl chloride (PVC), etc. Particularlysuitable high dielectric strength capping layer materials may includepolyketone (e.g., polyetherether ketone (“PEEK”)), polysulfide (e.g.,polyarylene sulfide), or a mixture thereof.

The capping layer is generally free of continuous fibers. That is, thecapping layer contains less than about 10 wt. % of continuous fibers, insome embodiments about 5 wt. % or less of continuous fibers, and in someembodiments, about 1 wt. % or less of continuous fibers (e.g., 0 wt. %).Nevertheless, the capping layer may contain other additives forimproving the final properties of the rod. Additive materials employedat this stage may include those that are not suitable for incorporatinginto the continuous fiber material. For instance, it may be desirable toadd pigments to reduce finishing labor, or it may be desirable to addflame retardant agents to enhance the flame retarding features of therod. Because many additive materials are heat sensitive, an excessiveamount of heat may cause them to decompose and produce volatile gases.Therefore, if a heat sensitive additive material is extruded with animpregnation resin under high heating conditions, the result may be acomplete degradation of the additive material. Additive materials mayinclude, for instance, mineral reinforcing agents, lubricants, flameretardants, blowing agents, foaming agents, ultraviolet light resistantagents, thermal stabilizers, pigments, and combinations thereof.Suitable mineral reinforcing agents may include, for instance, calciumcarbonate, silica, mica, clays, talc, calcium silicate, graphite,calcium silicate, alumina trihydrate, barium ferrite, and combinationsthereof.

While not shown in detail herein, the capping die 672 may includevarious features known in the art to help achieve the desiredapplication of the capping layer. For instance, the capping die 672 mayinclude an entrance guide that aligns the incoming rod. The capping diemay also include a heating mechanism (e.g., heated plate) that pre-heatsthe rod before application of the capping layer to help ensure adequatebonding. Following capping, the shaped part 615, or rod 750, is thenfinally cooled using a cooling system 680 as is known in the art. Thecooling system 680 may, for instance, be a sizing system that includesone or more blocks (e.g., aluminum blocks) that completely encapsulatethe rod while a vacuum pulls the hot shape out against its walls as itcools. A cooling medium may be supplied to the sizer, such as air orwater, to solidify the rod in the correct shape.

Even if a sizing system is not employed, it is generally desired to coolthe rod 750 after it exits the capping die (or the consolidation orcalibration die if capping is not applied). Cooling may occur using anytechnique known in the art, such a water tank, cool air stream or airjet, cooling jacket, an internal cooling channel, cooling fluidcirculation channels, etc. Regardless, the temperature at which thematerial is cooled is usually controlled to achieve optimal mechanicalproperties, part dimensional tolerances, good processing, and anaesthetically pleasing composite. For instance, if the temperature ofthe cooling station is too high, the material might swell in the tooland interrupt the process. For semi-crystalline materials, too low of atemperature can likewise cause the material to cool down too rapidly andnot allow complete crystallization, thereby jeopardizing the mechanicaland chemical resistance properties of the composite. Multiple coolingdie sections with independent temperature control can be utilized toimpart the optimal balance of processing and performance attributes. Inone particular embodiment, for example, a water tank is employed that iskept at a temperature of from about 0° C. to about 30° C., in someembodiments from about 1° C. to about 20° C., and in some embodiments,from about 2° C. to about 15° C.

If desired, one or more sizing blocks (not shown) may also be employed,such as after capping. Such blocks contain openings that are cut to theexact rod shape, graduated from oversized at first to the final rodshape. As the rod passes therethrough, any tendency for it to move orsag is counteracted, and it is pushed back (repeatedly) to its correctshape. Once sized, the rod may be cut to the desired length at a cuttingstation (not shown), such as with a cut-off saw capable of performingcross-sectional cuts or the rod can be wound on a reel in a continuousprocess. The length of rod will then be limited to the length of thefiber tow.

As will be appreciated, the temperature of the rod as it advancesthrough any section of the system of the present invention may becontrolled to yield optimal manufacturing and desired final compositeproperties. Any or all of the assembly sections may be temperaturecontrolled utilizing electrical cartridge heaters, circulated fluidcooling, etc., or any other temperature controlling device known tothose skilled in the art.

Referring again to FIG. 13, a pulling device 682 is positioneddownstream from the cooling system 680 that pulls the finished 750through the system for final sizing of the composite. The pulling device682 may be any device capable of pulling the rod through the processsystem at a desired rate. Typical pulling devices include, for example,caterpillar pullers and reciprocating pullers.

The rods 750 that result from use of dies and methods according to thepresent disclosure may have a very low void fraction, which helpsenhance their strength. For instance, the void fraction may be about 5%or less, in some embodiments about 4% or less, in some embodiments about3% or less, in some embodiments about 2% or less, in some embodimentsabout 1.5% or less, in some embodiments about 1% or less, and in someembodiments, about 0.5% or less. The void fraction may be measured usingtechniques well known to those skilled in the art. For example, the voidfraction may be measured using a “resin burn off” test in which samplesare placed in an oven (e.g., at 600° C. for 3 hours) to burn out theresin. The mass of the remaining fibers may then be measured tocalculate the weight and volume fractions. Such “burn off” testing maybe performed in accordance with ASTM D 2584-08 to determine the weightsof the fibers and the polymer matrix, which may then be used tocalculate the “void fraction” based on the following equations:

V _(f)=100*(ρ_(t)−ρ_(c))/ρ_(t)

where,

V_(f) is the void fraction as a percentage;

ρ_(c) is the density of the composite as measured using knowntechniques, such as with a liquid or gas pycnometer (e.g., heliumpycnometer);

ρ_(t) is the theoretical density of the composite as is determined bythe following equation:

ρ_(t)=1/[W _(f)/ρ_(f) +W _(m)/ρ_(m)]

ρ_(m) is the density of the polymer matrix (e.g., at the appropriatecrystallinity);

ρ_(f) is the density of the fibers;

W_(f) is the weight fraction of the fibers; and

W_(m) is the weight fraction of the polymer matrix.

Alternatively, the void fraction may be determined by chemicallydissolving the resin in accordance with ASTM D 3171-09. The “burn off”and “dissolution” methods are particularly suitable for glass fibers,which are generally resistant to melting and chemical dissolution. Inother cases, however, the void fraction may be indirectly calculatedbased on the densities of the polymer, fibers, tape and/or rod inaccordance with ASTM D 2734-09 (Method A), where the densities may bedetermined ASTM D792-08 Method A. Of course, the void fraction can alsobe estimated using conventional microscopy equipment.

As discussed above, after exiting an impregnation die 150, 412, the CFRTmaterial may in some embodiments form a tape 152, 156. The number ofrovings employed in each tape 152, 156 may vary. Typically, however, atape 152, 156 will contain from 2 to 80 rovings, and in some embodimentsfrom 10 to 60 rovings, and in some embodiments, from 20 to 50 rovings.In some embodiments, it may be desired that the rovings are spaced apartapproximately the same distance from each other within the tape 152,156. In other embodiments, however, it may be desired that the rovingsare combined, such that the fibers of the rovings are generally evenlydistributed throughout the tape 152, 156, such as throughout one or moreresin rich portions and a fiber rich portion as discussed above. Inthese embodiments, the rovings may be generally indistinguishable fromeach other. Referring to FIGS. 18 and 19, for example, embodiments of atape 152, 156 are shown that contains rovings that are combined suchthat the fibers 400 are generally evenly distributed therein. As shownin FIG. 18, in exemplary embodiments, the fibers extend generallyunidirectionally, such as along a longitudinal axis of the tape 152,156.

Through use of apparatus and methods according to the present disclosureand control over the various parameters mentioned above, tapes and rodshaving a very high strength may be formed. For example, the rods mayexhibit a high maximum load. Maximum load may be determined according toASTM D3039. The maximum load may be, for example, greater than about 290pounds per square inch (psi), or for example greater than about 130kilograms per square inch (130 ksi).

The rods may exhibit a relatively high flexural modulus. The term“flexural modulus” generally refers to the ratio of stress to strain inflexural deformation (units of force per area), or the tendency for amaterial to bend. It is determined from the slope of a stress-straincurve produced by a “three point flexural” test (such as ASTM D790-10,Procedure A), typically at room temperature. For example, the rod of thepresent invention may exhibit a minimum flexural modulus of about 10Gigapascals (“GPa”), in some embodiments a flexural modulus from about12 to about 400 GPa, in some embodiments a flexural modulus from about15 to about 200 GPa, and in some embodiments a flexural modulus fromabout 20 to about 150 GPa. Furthermore, the ultimate tensile strength ofa rod may be between approximately 280,000 pounds per square inch andapproximately 370,000 pounds per square inch, such as betweenapproximately 320,000 pounds per square inch and approximately 370,000pounds per square inch. The term “ultimate tensile strength” generallyrefers to the maximum stress that a material can withstand while beingstretched or pulled before necking and is the maximum stress reached ona stress-strain curve produced by a tensile test (such as ASTM D3916-08)at room temperature. The minimum tensile modulus of elasticity may alsobe about 50 GPa, or in some embodiments the tensile modulus ofelasticity may be from about 70 GPa to about 500 GPa, or in someembodiments the tensile modulus of elasticity may be from about 100 GPato about 300 GPa. The term “tensile modulus of elasticity” generallyrefers to the ratio of tensile stress over tensile strain and is theslope of a stress-strain curve produced by a tensile test (such as ASTM3916-08) at room temperature. Notably, the strength properties of thecomposite rod referenced above may also be maintained over a relativelywide temperature range, such as from about −40° C. to about 300° C., andparticularly from about 180° C. to 200° C.

Rods made according to the present disclosure may further haverelatively high flexural fatigue life, and may exhibit relatively highresidual strength. Flexural fatigue life and residual flexural strengthmay be determined based on a “three point flexural fatigue” test (suchas ASTM D790, typically at room temperature. For example, the rods ofthe present invention may exhibit residual flexural strength after onemillion cycles at 160 Newtons (“N”) or 180 N loads of from about 60kilograms per square inch (“ksi”) to about 115 ksi, in some embodimentsabout 70 ksi to about 115 ksi, and in some embodiments about 95 ksi toabout 115 ksi. Further, the rods may exhibit relatively minimalreductions in flexural strength. For example, rods having void fractionsof about 4% or less, in some embodiments about 3% or less, may exhibitreductions in flexural strength after three point flexural fatiguetesting of about 1% (for example, from a maximum pristine flexuralstrength of about 106 ksi to a maximum residual flexural strength ofabout 105 ksi). Flexural strength may be tested before and after fatiguetesting using, for example, a three point flexural test as discussedabove.

The linear thermal expansion coefficient of the composite rod may be, ona ppm basis per ° C., less than about 5, less than about 4, less thanabout 3, or less than about 2. For instance, the coefficient (ppm/° C.)may be in a range from about −0.25 to about 5; alternatively, from about−0.17 to about 4; alternatively, from about −0.17 to about 3;alternatively, from about −0.17 to about 2; or alternatively, from about0.29 to about 1.18. The temperature range contemplated for this linearthermal expansion coefficient may be generally in the −50° C. to 200° C.range, the 0° C. to 200° C. range, the 0° C. to 175° C. range, or the25° C. to 150° C. range. The linear thermal expansion coefficient ismeasured in the longitudinal direction, i.e., along the length of thefibers.

The composite rod may also exhibit a relatively small “bend radius”,which is the minimum radius that the rod can be bent without breakingand is measured to the inside curvature of the rod. A smaller bendradius means that the rod is more flexible and can be spooled onto asmaller diameter bobbin. This property also makes the rod easier toimplement in processes that currently use metal rods. Due to theimproved process and resulting rod of the present invention, bendradiuses may be achieved that are less than about 40 times the outerdiameter of the rod, in some embodiments from about 1 to about 30 timesthe outer diameter of the rod, and in some embodiments, from about 2 toabout 25 times the outer diameter of the rod, determined at atemperature of about 25° C. For instance, the bend radius may be lessthan about 15 centimeters, in some embodiments from about 0.5 to about10 centimeters, and in some embodiments, from about 1 to about 6centimeters, determined at a temperature of about 25° C.

These and other modifications and variations of the present inventionmay be practiced by those of ordinary skill in the art, withoutdeparting from the spirit and scope of the present invention. Inaddition, it should be understood that aspects of the variousembodiments may be interchanged both in whole or in part. Furthermore,those of ordinary skill in the art will appreciate that the foregoingdescription is by way of example only, and is not intended to limit theinvention so further described in such appended claims.

What is claimed is:
 1. A sucker rod assembly, the sucker rod assemblycomprising: a plurality of continuous fiber reinforced thermoplasticrods arranged in a stranded bundle, each of the plurality of continuousfiber reinforced thermoplastic rods having a core comprising a pluralityof generally unidirectionally oriented continuous fibers embedded in athermoplastic resin; and a first end fitting and a second end fitting,at least one of the first and second end fittings connected to theplurality of continuous fiber reinforced thermoplastic rods, whereineach of the plurality of rods has an ultimate tensile strength ofbetween approximately 280,000 pounds per square inch and approximately370,000 pounds per square inch, wherein the continuous fibers have aratio of ultimate tensile strength to mass per unit length of greaterthan about 1,000 Megapascals per gram per meter, and wherein thecontinuous fibers constitute from about 25 wt. % to about 80 wt. % ofeach of the plurality of rods and the thermoplastic resin constitutesfrom about 20 wt. % to about 75 wt. % of each of the plurality of rods.2. The sucker rod assembly of claim 1, wherein each of the plurality ofrods has an ultimate tensile strength of between approximately 320,000pounds per square inch and approximately 370,000 pounds per square inch.3. The sucker rod assembly of claim 1, wherein the continuous fibershave a ratio of ultimate tensile strength to mass per unit length offrom about 5,000 to about 20,000 Megapascals per gram per meter.
 4. Thesucker rod assembly of claim 1, wherein the continuous fibers are carbonfibers.
 5. The sucker rod assembly of claim 1, wherein the thermoplasticresin includes a polyarylene sulfide.
 6. The sucker rod assembly ofclaim 5, wherein the polyarylene sulfide is polyphenylene sulfide. 7.The sucker rod assembly of claim 1, wherein the continuous fibersconstitute from about 30 wt. % to about 75 wt. % of each of theplurality of rods.
 8. The sucker rod assembly of claim 1, wherein thecore of each of the plurality of rods has a void fraction of about 3% orless.
 9. The sucker rod assembly of claim 1, wherein each of theplurality of rods has a minimum flexural modulus of about 10Gigapascals.
 10. The sucker rod assembly of claim 1, wherein each of theplurality of rods has a minimum tensile modulus of elasticity of about50 Gigapascals.
 11. The sucker rod assembly of claim 1, wherein each ofthe plurality of rods has a bend radius of from about 0.5 to about 10centimeters.
 12. The sucker rod assembly of claim 1, further comprisinga capping layer surrounding the core of each of the plurality of rods.13. The sucker rod assembly of claim 12, wherein the capping layerincludes polyetherether ketone.
 14. The sucker rod assembly of claim 12,wherein the capping layer is free from fibers.
 15. A sucker rodassembly, the sucker rod assembly comprising: a single monolithiccontinuous fiber reinforced thermoplastic rod, the continuous fiberreinforced thermoplastic rod having a core and a capping layersurrounding the core, the core comprising a plurality of generallyunidirectionally oriented continuous fibers embedded in a thermoplasticresin, wherein the fibers are carbon fibers and the thermoplastic resinincludes a polyarylene sulfide, the capping layer includingpolyetherether ketone and free from fibers; and a first end fitting anda second end fitting, at least one of the first and second end fittingsconnected to the continuous fiber reinforced thermoplastic rod, whereinthe continuous fiber reinforced thermoplastic rod has an ultimatetensile strength of between approximately 280,000 pounds per square inchand approximately 370,000 pounds per square inch, and wherein thecontinuous fibers constitute from about 25 wt. % to about 80 wt. % ofthe rod and the thermoplastic resin constitutes from about 20 wt. % toabout 75 wt. % of the rod.
 16. The sucker rod assembly of claim 15,wherein the continuous fiber reinforced thermoplastic rod has anultimate tensile strength of between approximately 320,000 pounds persquare inch and approximately 370,000 pounds per square inch.
 17. Thesucker rod assembly of claim 15, wherein the polyarylene sulfide ispolyphenylene sulfide.
 18. The sucker rod assembly of claim 15, whereinthe continuous fibers constitute from about 30 wt. % to about 75 wt. %of the rod.
 19. The sucker rod assembly of claim 15, wherein the core ofthe rod has a void fraction of about 3% or less.
 20. The sucker rodassembly of claim 15, wherein the rod has a minimum flexural modulus ofabout 10 Gigapascals.
 21. The sucker rod assembly of claim 15, whereinthe rod has a minimum tensile modulus of elasticity of about 50Gigapascals.
 22. The sucker rod assembly of claim 15, wherein the rodhas a bend radius of from about 0.5 to about 10 centimeters.